title: Negative appendectomy and imaging accuracy in the Washington State Surgical Care and Outcomes Assessment Program.
abstract: OBJECTIVE
  To evaluate negative appendectomy (NA) and the relationship of NA and computed tomography (CT) and/or ultrasound (US). SUMMARY BACKGROUND INFORMATION: NA may be influenced by the use and accuracy of preoperative CT/US. The Surgical Care and Outcomes Assessment Program (SCOAP) gathers chart-abstracted process of care data (such as CT/US accuracy) for general surgical procedures (including appendectomy) at most Washington State hospitals.
  
  
  METHODS
  We determined the prevalence of NA and CT/US concordance at the 15 SCOAP hospitals with >50 consecutive patients undergoing appendectomy (2006-2007).
  
  
  RESULTS
  The number of patients who underwent urgent appendectomies was 3540. The percentage of patients who had imaging (CT-91%) was 86% (women-89%, men-83%). The use of imaging ranged across hospitals from 56% to 97%. There was 91% agreement between imaging and pathology report findings (92.3%-CT and 82.4%-US). The overall rate of NA was 6% (women-8%, men-4%). The prevalence of NA was 9.8% among patients having no imaging, 8.1% among those having an US, and 4.5% in those having a CT. Among patients with NA, CT/US was obtained in 75%; correct in 10% and incorrect or ambiguous in 65%. Higher rates of NA were correlated with lower rates of CT/US concordance (r = -0.57). There was no significant difference in rates of perforation between those with (17%) and without (15%) imaging (P = 0.2). There were significant increases in the use of CT/US and decreases in NA over the time period (P < 0.01).
  
  
  CONCLUSIONS
  The prevalence of NA at SCOAP hospitals decreased significantly. Variation in NA between hospitals was linked closely to CT/US accuracy suggesting CT/US accuracy should be considered a measure of quality in the care of patients with presumed appendicitis.
authors.affiliation: Department of Surgery, University of Washington, Seattle, WA, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Cuschieri
authors.forename: Michael
authors.initials: M
authors.lastname: Florence
authors.forename: David R
authors.initials: DR
authors.lastname: Flum
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Jurkovich
authors.forename: Paul
authors.initials: P
authors.lastname: Lin
authors.forename: Scott R
authors.initials: SR
authors.lastname: Steele
authors.forename: Rebecca Gaston
authors.initials: RG
authors.lastname: Symons
authors.forename: Richard
authors.initials: R
authors.lastname: Thirlby
mesh_terms: D000328:Adult; D001062:Appendectomy / Q000706:statistics & numerical data*; D001064:Appendicitis / Q000175:diagnosis* / Q000601:surgery; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D003952:Diagnostic Imaging / Q000592:standards*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011300:Preoperative Care / Q000379:methods; D011446:Prospective Studies; D012307:Risk Factors; D019564:Unnecessary Procedures / Q000706:statistics & numerical data*; D014861:Washington